<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>

</body>
</html>

<script>
	// var sum = 0;
	// var i = 1;
	// do{
	// 	sum+=i;
	// 	i++

	// }while(i<=100);

	// document.write(sum)
	var sum=0;
	for(var i=1;i<=100;i++){
		if(i%2==0){
			sum-=1/i;
		}else{
			sum+=1/i;
		}
	}

	document.write(sum);

</script>